This invention relates to auxiliary insulating window assemblies which may be attached to the inside wall of mobile homes, trailers and other portable shelter units. These auxiliary insulating windows surround the existing built-in window and frame, providing additional heat insulation in cold weather conditions.
Typically, motor homes, mobile homes and other portable shelter units are built of relatively lightweight, poorly insulated materials and utilize both venting and fixed window assemblies. Those windows which can be opened for ventilation frequently utilize a crank handle protruding into the living quarters of the portable shelter unit in order to crank open or close the windows. While this handle is removable, the stem to which it attaches and through which it activates the linkage of the window continues to protrude from the window frame. Thus, any auxiliary insulating window assembly to be attached over the existing window must be spaced outwardly from the wall enough to allow room for this handle stem Under the constant vibration of travel, and/or under the stress of expansion and contraction brought on by extremes of weather, as in the case of motor homes, experience has demonstrated that the frames of many existing insulating windows tend to sag, warp, or otherwise become separated from either the glass portion of the window assembly or from the wall of the portable shelter unit or both.
Certain prior art insulating frames utilize magnetic strips which allow an insulating window unit to be fastened directly to the metal frame of an existing window built into a portable shelter unit. However, this configuration provides minimal insulation and draft prevention, and does not allow room for the crank stem which protrudes from the frame of many types of windows.
It is known in the prior art to fasten a wood frame, as with two inch by two inch wood strips, to the wall of a portable shelter unit around the existing built-in window, and then fasten a storm window to that wood frame, thus providing some insulation and allowing room for the stem of the window crank handle. However, cracks and gaps are easily formed between the storm window and the wooden frame and the wooden frame and the wall, allowing drafts of cold outside air to enter and heated inside air to escape and this two by two construction is so labor intensive and expensive as to be impractical in most situations.
Most trailers, motor homes and other portable shelter units are extremely difficult to heat in cold weather. Their poor insulation and drafty windows combine to require large expenditures of heat energy and result in high heating bills. Typically such shelters are used by those who cannot afford conventional housing and who are ill equipped to pay large sums for custom made windows. Generally, large scale upgrading of the home's windows is possible only when bank financing can be obtained, and such financing is rigidly constrained by the collateral defined by the low overall cost of the shelter. Custom building windows to the shelter unit and building the described two by two frames generates so much cost as to create a total improvement cost that is such a large percentage of the home's value that banks and financiers will not grant loans for improvements because the total improved home value is inadequate as collateral. The present invention provides a functional window structure whose cost is so significantly reduced that financing can now be obtained, allowing such home owners a viable, warm alternative at an affordable price which allows utilization of bank financing.